In the past, avionics engineers have struggled with frequent interruptions and disturbances in the primary input power of avionics equipment. One particular problem resulting from such power disturbances has been the rapid cooling of filaments in a fluorescent lamp. One common way of dealing with this loss of power and concomitant reduction in filament temperature is to provide a standardized heating current to flow through the filaments while the arc power is disabled. In other situations, the arc power is immediately applied upon the end of the primary power interruption.
While these approaches to post primary power interruption lamp operation may have many advantages in particular uses, they also have significant drawbacks. One drawback of standardized heating current is that it often is set at a time of approximately six seconds and as such, is often far in excess of what is needed, especially if the primary power interruption lasted less than 50 ms. A drawback of the immediate provision of arc power is that it can cause damage to the lamp if done repeatedly.
Consequently, there exists a need for improved methods and apparatuses for driving fluorescent lamps after an interruption of primary power to the lamp.